Exam-style question
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If a star's apparent brightness is measured at 0.1 W/m² and it is located 5 parsecs away, what can be inferred about its luminosity?.
- A.The star has low luminosity.
- B.The star has high luminosity.
- C.The star's luminosity cannot be determined.
- D.The star's luminosity is equal to its apparent brightness.
Model answer
What a good answer should say
- The star has high luminosity.
Explanation
Why this works
Given the apparent brightness and distance, we can infer that the star must have a high luminosity to appear as bright as 0.1 W/m² at 5 parsecs, as brightness decreases with distance.
Common mistake
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